//
// Created by Thinkpad on 2025/11/9.
//

#include <iostream>
using namespace std;


const double PI = 3.141592653589;

class Cylinder {
private:
    double base_radius{1.0};
    double height{1.0};

public:
    Cylinder() = default;

    Cylinder(double radius_param, double height_param) {
        base_radius = radius_param;
        height = height_param;
    }

    double volume() {
        return PI * base_radius * base_radius * height;
    }
};

int main() {
    Cylinder cylinder1;
    cout << cylinder1.volume() << endl;
    return 0;
}
